fix(xray): guard log-writer race and bound handler gRPC deadlines (#5442)

* perf(xray): compile log/traffic regexps once at package scope

GetTraffic recompiled two stats regexps on every traffic tick, and LogWriter.Write
recompiled two more on every log line. Hoist all four to package-level vars so they
compile once at load instead of per call on hot paths.

* fix(xray): guard LogWriter.lastLine against the GetResult reader race

Write is driven by the Xray process goroutine while Process.GetResult
reads lastLine from the caller's goroutine, so the unsynchronized field
is a data race under `go test -race`. Add an RWMutex and route every
write through setLastLine; GetResult reads via LastLine().

* fix(xray): bound handler gRPC calls with a deadline

AddInbound, DelInbound and the AddUser AlterInbound call used
context.Background(), so a hung core connection could block the caller
indefinitely (for example while the process restart lock is held). Give
them a 10s deadline (handlerRPCTimeout) and a nil-client guard, matching
the other handler operations.

internal/xray/api.go

@@ -123,8 +123,16 @@ func (x *XrayAPI) Close() {
 	x.isConnected = false
 }
 
+// handlerRPCTimeout bounds per-call gRPC handler operations (add/remove inbound,
+// alter user) so a hung core connection cannot block the caller indefinitely —
+// for example while the process restart lock is held.
+const handlerRPCTimeout = 10 * time.Second
+
 // AddInbound adds a new inbound configuration to the Xray core via gRPC.
 func (x *XrayAPI) AddInbound(inbound []byte) error {
+	if x.HandlerServiceClient == nil {
+		return common.NewError("xray HandlerServiceClient is not initialized")
+	}
 	client := *x.HandlerServiceClient
 
 	conf := new(conf.InboundDetourConfig)
@@ -140,15 +148,22 @@ func (x *XrayAPI) AddInbound(inbound []byte) error {
 	}
 	inboundConfig := command.AddInboundRequest{Inbound: config}
 
-	_, err = client.AddInbound(context.Background(), &inboundConfig)
+	ctx, cancel := context.WithTimeout(context.Background(), handlerRPCTimeout)
+	defer cancel()
+	_, err = client.AddInbound(ctx, &inboundConfig)
 
 	return err
 }
 
 // DelInbound removes an inbound configuration from the Xray core by tag.
 func (x *XrayAPI) DelInbound(tag string) error {
+	if x.HandlerServiceClient == nil {
+		return common.NewError("xray HandlerServiceClient is not initialized")
+	}
 	client := *x.HandlerServiceClient
-	_, err := client.RemoveInbound(context.Background(), &command.RemoveInboundRequest{
+	ctx, cancel := context.WithTimeout(context.Background(), handlerRPCTimeout)
+	defer cancel()
+	_, err := client.RemoveInbound(ctx, &command.RemoveInboundRequest{
 		Tag: tag,
 	})
 	return err
@@ -505,9 +520,14 @@ func (x *XrayAPI) AddUser(Protocol string, inboundTag string, user map[string]an
 		return nil
 	}
 
+	if x.HandlerServiceClient == nil {
+		return common.NewError("xray HandlerServiceClient is not initialized")
+	}
 	client := *x.HandlerServiceClient
 
-	_, err = client.AlterInbound(context.Background(), &command.AlterInboundRequest{
+	ctx, cancel := context.WithTimeout(context.Background(), handlerRPCTimeout)
+	defer cancel()
+	_, err = client.AlterInbound(ctx, &command.AlterInboundRequest{
 		Tag: inboundTag,
 		Operation: serial.ToTypedMessage(&command.AddUserOperation{
 			User: &protocol.User{